<button class="button">Sign up now</button>
<style>
.button{
	padding:1em;
	border:0;
	font-size:0.8rem;
	color:white;
	border-radius:0.5em;
	background-image:linear-gradient(to bottom,#57b,#148);
	box-shadow:0.1em 0.1em 0.5em #124;
}
.button:active{
	box-shadow:inset 0 0 0.5em #124,inset 0 0.5em 1em rgba(0,0,0,0.4);
}
</style>